Search

Your search keyword '"RODRIGUES, L. F."' showing total 125 results
Start Over Author "RODRIGUES, L. F."
125 results on '"RODRIGUES, L. F."'

3. The Pencil Code, a modular MPI code for partial differential equations and particles: multipurpose and multiuser-maintained

Author

Brandenburg, A., Johansen, A., Bourdin, P. A., Dobler, W., Lyra, W., Rheinhardt, M., Bingert, S., Haugen, N. E. L., Mee, A., Gent, F., Babkovskaia, N., Yang, C. -C., Heinemann, T., Dintrans, B., Mitra, D., Candelaresi, S., Warnecke, J., Käpylä, P. J., Schreiber, A., Chatterjee, P., Käpylä, M. J., Li, X. -Y., Krüger, J., Aarnes, J. R., Sarson, G. R., Oishi, J. S., Schober, J., Plasson, R., Sandin, C., Karchniwy, E., Rodrigues, L. F. S., Hubbard, A., Guerrero, G., Snodin, A., Losada, I. R., Pekkilä, J., and Qian, C.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Physics - Fluid Dynamics
Abstract

The Pencil Code is a highly modular physics-oriented simulation code that can be adapted to a wide range of applications. It is primarily designed to solve partial differential equations (PDEs) of compressible hydrodynamics and has lots of add-ons ranging from astrophysical magnetohydrodynamics (MHD) to meteorological cloud microphysics and engineering applications in combustion. Nevertheless, the framework is general and can also be applied to situations not related to hydrodynamics or even PDEs, for example when just the message passing interface or input/output strategies of the code are to be used. The code can also evolve Lagrangian (inertial and noninertial) particles, their coagulation and condensation, as well as their interaction with the fluid., Comment: 7 pages, submitted to the Journal for Open Source Software (JOSS)

Published
2020
Full Text
View/download PDF

5. Fickian and non-Fickian diffusion of cosmic rays

Author

Rodrigues, L. F. S., Snodin, A. P., Sarson, G. R., and Shukurov, Anvar

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Fluid approximations to cosmic ray (CR) transport are often preferred to kinetic descriptions in studies of the dynamics of the interstellar medium (ISM) of galaxies, because they allow simpler analytical and numerical treatments. Magnetohydrodynamic (MHD) simulations of the ISM usually incorporate CR dynamics as an advection-diffusion equation for CR energy density, with anisotropic, magnetic field-aligned diffusion with the diffusive flux assumed to obey Fick's law. We compare test-particle and fluid simulations of CRs in a random magnetic field. We demonstrate that a non-Fickian prescription of CR diffusion, which corresponds to the telegraph equation for the CR energy density, can be easily calibrated to match the test particle simulations with great accuracy. In particular, we consider a random magnetic field in the fluid simulation that has a lower spatial resolution than that used in the particle simulation to demonstrate that an appropriate choice of the diffusion tensor can account effectively for the unresolved (subgrid) scales of the magnetic field. We show that the characteristic time which appears in the telegraph equation can be physically interpreted as the time required for the particles to reach a diffusive regime and we stress that the Fickian description of the CR fluid is unable to describe complex boundary or initial conditions for the CR energy flux., Comment: 6 pages, 5 figures. Accepted for publication in MNRAS

Published
2018
Full Text
View/download PDF

6. Global diffusion of cosmic rays

Author

Snodin, A. P., Shukurov, A., Sarson, G. R., Bushby, P. J., and Rodrigues, L. F. S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

The propagation of charged particles, including cosmic rays, in a partially ordered magnetic field is characterized by a diffusion tensor whose components depend on the particle's Larmor radius $R_L$ and the degree of order in the magnetic field. Most studies of the particle diffusion presuppose a scale separation between the mean and random magnetic fields (e.g., there being a pronounced minimum in the magnetic power spectrum at intermediate scales). Scale separation is often a good approximation in laboratory plasmas, but not in most astrophysical environments such as the interstellar medium (ISM). Modern simulations of the ISM have numerical resolution of order 1 pc, so the Larmor radius of the cosmic rays that dominate in energy density is at least $10^{6}$ times smaller than the resolved scales. Large-scale simulations of cosmic ray propagation in the ISM thus rely on oversimplified forms of the diffusion tensor. We take the first steps towards a more realistic description of cosmic ray diffusion for such simulations, obtaining direct estimates of the diffusion tensor from test particle simulations in random magnetic fields (with the Larmor radius scale being fully resolved), for a range of particle energies corresponding to $10^{-2}\lesssim R_L/l_c \lesssim 10^{3}$, where $l_c$ is the magnetic correlation length. We obtain explicit expressions for the cosmic ray diffusion tensor for $R_L/l_c \ll 1$, that might be used in a sub-grid model of cosmic ray diffusion. The diffusion coefficients obtained are closely connected with existing transport theories that include the random walk of magnetic lines., Comment: 13 pages, 12 figures, accepted for publication in MNRAS

Published
2015
Full Text
View/download PDF

7. Experimental Biogas Production and Biomethane Potential of Swine Wastewater Among Different Production Stages

Author

Lourinho, G., Brito, P. S. D., Rodrigues, L. F. T. G., Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Ruediger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Liang, Qilian, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zhang, Junjie James, Series Editor, Machado, José, editor, and Soares, Filomena, editor

Published
2019
Full Text
View/download PDF

10. Gravity complexes as a focus of seafloor fluid seepage : the Rio Grande Cone, SE Brazil

Author

Ketzer, João Marcelo, Praeg, D., Augustin, A. H., Rodrigues, L. F., Steiger, A. K., Rahmati-Abkenar, Mahboubeh, Viana, A. R., Miller, D. J., Malinverno, A., Dickens, G. R., Cupertino, J. A., Ketzer, João Marcelo, Praeg, D., Augustin, A. H., Rodrigues, L. F., Steiger, A. K., Rahmati-Abkenar, Mahboubeh, Viana, A. R., Miller, D. J., Malinverno, A., Dickens, G. R., and Cupertino, J. A.

Abstract

Seafloor methane emissions can affect Earth’s climate and ocean chemistry. Vast quantities of methane formed by microbial decomposition of organic matter are locked within gas hydrate and free gas on continental slopes, particularly in large areas with high sediment accumulations such as deep-sea fans. The release of methane in slope environments has frequently been associated with dissociation of gas hydrates near the edge of the gas hydrate stability zone on the upper slope, with discharges in greater water depths less understood. Here we show, using data from the Rio Grande Cone (western South Atlantic), that the intrinsic, gravity-induced downslope collapse of thick slope sediment accumulations creates structures that serve as pathways for gas migration, unlocking methane and causing seafloor emissions via giant gas flares in the water column. The observed emissions in the study region (up to 310 Mg year−1) are three times greater than estimates for the entire US North Atlantic margin and reveal the importance of collapsing sediment accumulations for ocean carbon cycling. Similar outgassing systems on the Amazon and Niger fans suggest that gravity tectonics on passive margins is a common yet overlooked mechanism driving massive seafloor methane emissions in sediment-laden continental slopes. © 2023, The Author(s).

Published
2023
Full Text
View/download PDF

12. Characterization of a pollution source with isotopic and physicochemical measurements using a forensic metrology approach.

Author

Barbieri, Cristina Barazetti, Sarkis, J. E. S., and Rodrigues, L. F.

Subjects
HAZARDOUS wastes, POLLUTION, METROLOGY, ISOTOPIC analysis, ISOTOPIC signatures, ENVIRONMENTAL crimes
Abstract

Carbon and nitrogen composition and isotopic ratios (δ15N, δ13C, and δ13C-DIC) as well as physicochemical parameters were measured in hazardous waste leachate connected to an environmental pollution crime. A forensic metrology approach was employed by estimating the measurement uncertainty, including that from the sampling process, using range statistics. The physicochemical parameters demonstrated differences in the leachate from some of the different ponds and this was supported by carbon and nitrogen elemental and isotopic analyses. The isotopic signature of δ15N and δ13C-DIC was highly enriched in the heavy isotope demonstrating that those analyses are a substantial tool for leachate pollution tracking. The uncertainty of the measurements was below or slightly above 20% for most parameters which can be considered fit-for-purpose for a great deal of environmental surveys and was remarkably lower in the isotopic analyses. The uncertainty of measurement including the primary sampling is a relevant information in environmental investigations, especially forensic ones. This knowledge is crucial for a consistent interpretation of environmental samples analyses results, specially from polluted sites and pollution source characterization and tracking, where there is often substantial heterogeneity in environmental samples. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

31. Evolution of galactic magnetic fields.

Author

Rodrigues, L F S, Chamandy, L, Shukurov, A, Baugh, C M, and Taylor, A R

Subjects
*GALACTIC magnetic fields, *GALACTIC evolution, *STAR formation, *SYMMETRY (Physics), *ASTRONOMICAL observations
Abstract

We study the cosmic evolution of the magnetic fields of a large sample of spiral galaxies in a cosmologically representative volume by employing a semi-analytic galaxy formation model and numerical dynamo solver in tandem. We start by deriving time- and radius-dependent galaxy properties using the galform galaxy formation model, which are then fed into the non-linear mean-field dynamo equations. These are solved to give the large-scale (mean) field as a function of time and galactocentric radius for a thin disc, assuming axial symmetry. A simple prescription for the evolution of the small-scale (random) magnetic field component is also adopted. We find that, while most massive galaxies are predicted to have large-scale magnetic fields at redshift |$z$|  = 0, a significant fraction of them is expected to contain negligible large-scale field. Our model indicates that, for most of the galaxies containing large-scale magnetic fields today, the mean-field dynamo becomes active at |$z$| < 3. Moreover, the typical magnetic field strength at any given galactic stellar mass is predicted to decline with time up until the present epoch, in agreement with our earlier results. We compute the radial profiles of pitch angle, and find broad agreement with observational data for nearby galaxies. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

36. Electrodeposition of Zn-Mn alloys from recycling battery leach solutions in the presence of amines

Author

Brito, P. S. D., Patrício, S., Rodrigues, L. F., Santos, D. M. F., and Sequeira, C. A. C.

Subjects
Zn-MnO2, battery recycling, electrolyte additives, Zn-Mn electrodeposition
Abstract

The recovery of metal ions by electrodeposition from solutions resulting from the lixiviation of spent Zn-MnO2 batteries was studied. It was attempted to optimise the electrodeposition process, the selectivity of ion-separation, the morphologic characteristics, and the anticorrosive and galvanic properties of metallic deposits. The simultaneous deposition of zinc and manganese on different ferrous substrates under various experimental conditions was tested. This allowed us to access the efficiency of the electrodeposition, the morphology and composition of the metallic deposits, as well as their performance as galvanic coating layers. The effect of amine additives, namely, of methylamine and ethylenediamine, on the properties of the coatings was also studied. It was shown that the amines with buffering or passivating effects improve the simultaneous deposition of Mn.

Published
2010

37. The Chemistry CATT-BRAMS model (CCATT-BRAMS 4.5): a regional atmospheric model system for integrated air quality and weather forecasting and research

Author

Longo, K. M., primary, Freitas, S. R., additional, Pirre, M., additional, Marécal, V., additional, Rodrigues, L. F., additional, Panetta, J., additional, Alonso, M. F., additional, Rosário, N. E., additional, Moreira, D. S., additional, Gácita, M. S., additional, Arteta, J., additional, Fonseca, R., additional, Stockler, R., additional, Katsurayama, D. M., additional, Fazenda, A., additional, and Bela, M., additional

Published
2013
Full Text
View/download PDF

45. The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) – Part 1: Model description and evaluation

Author

Freitas, S. R., primary, Longo, K. M., additional, Silva Dias, M. A. F., additional, Chatfield, R., additional, Silva Dias, P., additional, Artaxo, P., additional, Andreae, M. O., additional, Grell, G., additional, Rodrigues, L. F., additional, Fazenda, A., additional, and Panetta, J., additional

Published
2009
Full Text
View/download PDF

48. Supplementary material to &quot;The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) – Part 1: Model description and evaluation&quot;

Author

Freitas, S. R., primary, Longo, K. M., additional, Silva Dias, M. A. F., additional, Chatfield, R., additional, Silva Dias, P., additional, Artaxo, P., additional, Andreae, M. O., additional, Grell, G., additional, Rodrigues, L. F., additional, Fazenda, A., additional, and Panetta, J., additional

Published
2007
Full Text
View/download PDF

49. The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) – Part 1: Model description and evaluation

Author

Freitas, S. R., primary, Longo, K. M., additional, Silva Dias, M. A. F., additional, Chatfield, R., additional, Silva Dias, P., additional, Artaxo, P., additional, Andreae, M. O., additional, Grell, G., additional, Rodrigues, L. F., additional, Fazenda, A., additional, and Panetta, J., additional

Published
2007
Full Text
View/download PDF

50. Eficiência do protocolo ovsynch em ovelhas da raça Santa Inês

Author

Oliveira, M. E. F., primary, Rodrigues, L. F. S., additional, Almeida, O. M., additional, Cordeiro, M. F., additional, Moura, A. C. B., additional, Sousa, H. L. L., additional, Loureiro, F. N., additional, Teixeira, P. P. M., additional, Penha Filho, M. M., additional, and Vicente, W. R. R., additional

Published
2007
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results